The present invention relates to a catalyst for use in the preparation of ethylene homopolymers and copolymers by means of a catalyst system which contains:
(1) reduced titanium tetrachloride or other tetravalent titanium compound, and PA1 (2) an aluminum alkyl of the formula ##STR1## where X and Y are each alkyl of not more than 8, especially not more than 4, carbon atoms, and Z is chlorine or alkyl of not more than 8, especially not more than 4, carbon atoms. PA1 (1) reduced titanium tetrachloride or other tetravalent titanium compound, and PA1 (2) an aluminum alkyl of the formula ##STR3## where X and Y are each alkyl of not more than 8, especially not more than 4, carbon atoms, and Z is chlorine or alkyl of not more than 8, especially not more than 4, carbon atoms, and PA1 (3) a catalyst support material comprising a substituted polystyrene resin wherein the substituent groups are selected from the group consisting of hydroxymethyl, chloromethyl, and sulphonate, and the support material has been treated with a magnesium salt to form an active support. The substituent groups are substituted on the phenyl rings of the polystyrene resin.
More specifically, the invention relates to complex catalysts wherein a magnesium salt-modified polymeric material is utilized as a support for the two components described above in order to increase the effective surface area of the catalyst and thereby its activity and productivity.
The use of polymeric materials as catalyst supports has been known for some time. Belgium Pat. No. 552,550 discloses the use of preformed polyethylene as an inert support. British Pat. No. 834,217 discloses the use of a cellulose resin. U.S. Pat. No. 3,396,155, issued Aug. 6, 1968, discloses the use of vinyl alcohol copolymers as support materials wherein the titanium compound is substituted at the hydroxyl groups in the chain. Nitrogen-containing polymers having amino-, imino-, imido-, urethane-, nitrile-, or nitro-groups are disclosed in Belgium Pat. No. 706,659 and sulfur-containing polymers, such as polysulphone, are disclosed in Belgium Pat. No. 690,008. Carbon chain polymers having fragments containing elements with unshared pairs of electrons, such as nitrogen, oxygen, sulfur, and phosphorous, are disclosed in Inventors Certificate of the U.S.S.R. No. 420,330. Polymer carriers containing groups such as &gt;C.dbd.O, &gt;.tbd.N, and C.dbd.N are disclosed in Belgium Pat. No. 716,375. Finally, U.S. Pat. No. 4,147,664, issued Apr. 3, 1979, discloses polymeric catalysts support materials which contain a substituted polymeric fragment. The aluminum component or the titanium component is reacted with the substituted fragment and thus is attached to the polymer chain. The substituents disclosed are --OH, --NHR, --SR, --COCH.sub.3, --CH.sub.2 OH, ##STR2## --CH.sub.2 NHR, --CH.sub.2 SH, --COOH, --OCOCH.sub.3, --COOCH.sub.3, --C.tbd.N, --N(R).sub.2, --SO.sub.2 R, --SOR, --CH.sub.2 S--CH.sub.2 CH.dbd.CH.sub.2, --CH.sub.2 --NH--CH.sub.2 CH.dbd.CH.sub.2, --CH.sub.2 --SO.sub.2 --CH.dbd.CH.sub.2 and ring compounds containing nitrogen, wherein R is hydrogen, methyl, ethyl, phenyl, or CH.sub.2 .dbd.CH--.
In all of the support materials described in the above prior art patents, the aluminum or titanium compounds are attached either directly to the polymer chain or through a substituent group which is itself directly grafted onto the polymer chain. In the present invention, the use of a polystyrene resin which contains substituent groups attached to the phenyl groups of the polystyrene chain provides advantages over the above in terms of ability to bind magnesium ions which form a polymeric ionic magnesium support for the attachment of titanium to the support.